Abstract 16232: Comparative Effects of Weight Loss on Ventricular Repolarization in Normotensive Morbidly Obese Patients With and Without Heart Failure
Background: Delayed ventricular repolarization has been reported in obese patients and improves with weight loss. Factors responsible for these observations have not been identified. This study compares the corrected QT interval (QTc) and QTc dispersion in normotensive morbidly obese subjects with and without heart failure (HF) prior to and following substantial weight loss from bariatric surgery.
Methods: The study population consisted of 28 patients with HF (Framingham criteria) and 39 patients without HF. Body mass index (BMI) was ≥ 40 kg/m2 and blood pressure was < 140/90 mmHg in all patients. An electrocardiogram and transthoracic echocardiogram were performed prior to surgery and at the nadir of post-operative weight loss. Bazett's formula was used to calculate QTc. QTc dispersion was calculated by subtracting the minimum from the maximum QTc on the 12 lead electrocardiogram. Echocardiographic left ventricular (LV) mass was calculated using the formula of Devereux and Reichek and was indexed to height.
Results: Mean BMI, LV mass/height, QTc and QTc dispersion were significantly greater/longer in patients with than without HF (p< 0.001 for all). Weight loss produced significant reductions in mean BMI, LV mass/height, QTc and QTc dispersion in subgroups with and without HF (p < 0.01 for all). However, the weight loss-related decreases in these variables were significantly greater in patients with HF than in those without HF. Respective reductions in patients with and without HF were as follows: BMI (-12.6 ± 2.4 vs.-10.0 ± 2.7 kg/m2, p=0.025); LV mass/height (-65.3 ± 10.5 vs.-45.9 ± 23.6 g/m, p=0.01); QTc (-28.3 ± 10.6 vs.17.2 ± 14.4 msec, p=0.01); and QTc dispersion (-19.4 ± 9.3 vs.11.7 ± 10.4 msec, p=0.01).
Conclusions: QTc is longer and QTc dispersion is greater in normotensive morbidly obese patients with HF than in those without HF. Both variables decrease to a greater extent in patients with HF than in those without HF In this population LV mass is an important determinant of pre-weight loss QTc and QTc dispersion and of the response of QTc and QTc dispersion to weight loss.
- © 2011 by American Heart Association, Inc.